1. Field of the Invention
The present invention relates to a vehicle seat with a suspension device, and particularly is concerned with a structure of the suspension device in the seat equipped with a set belt anchor.
2. Description of the Prior Art
In some of vehicles, especially automobiles, a suspension device is provided between the seat and floor for the purpose of resiliently supporting the seat to absorb a vibration or shock caused during driving on a rough road.
In most instances, a suspension device of this kind has X-shaped links are provided between an upper frame connected to a seat and a lower frame fixed on the side of floor of automobile body such that the upper frame is vertically movable via the X-shaped links relative to the lower frame, and a spring is extended between the X-shaped links and those frames, with a shock absorber being interposed between the upper and lower frames, whereby with this structure, the suspension action is performed by virtue of the spring and shock absorber.
The seat provided with such suspension device has created problems in anchoring seat belts anchor thereon, in that the structure of the belt anchors involve a high possibility, that a great impact will cause damage to the suspension device and excessive pressure through the seat belt on the occupant. For example, when the belt anchor is fixed on the seat or the upper frame of the suspension device, an accidental collision accident may result in the occupant being thrown out of the automobile. On the other hand, in the case of the belt anchor fixed on the floor, the vertical movement of the suspension device, even in driving on a normal road, causes undesired excessive fastening of the seat belt around the occupant.
In view of the foregoing problem, there has been proposed a dual belt anchor structure consisting of a first belt anchor fixed on the set or the upper frame of suspension device and a second belt anchor fixed on the side of vehicle floor, wherein the first belt anchor is connected with the second belt anchor via a second belt or link, so that, in a collision accident, a reaction force exerted by the occupant to the seat belt is transmitted and passed to the floor.
However, the above-mentioned dual belt anchor structure employed in conventional seat with suspension device is found disadvantageous in its complexity due to the fact that the two belt anchors as well as the second belt or link are required for installation of a seat belt on the seat, and further has a shortcoming in that the second belt needs to be adjusted its length so as to be loosened, considering the stroke amount of vertical movement of the suspension device as well as the movement range of slide rails, and the degree of loosening of the second belt varies depending on different forward/backward positions of the seat adjusted by the occupant, which makes the occupant feel uneasy about the unstable state of seat belt and hard to trust the seat belt in sitting on the seat.
To solve the above-mentioned problems, the the inventor of the present invention has proposed an improvement in the seat with suspension device which is now issued under the U.S. Pat. No. 4,813,645 according to which, in its X-shaped link type suspension device, there is provided halfway engagement means at the upper frame thereof and a slidable engagement link means is provided between the halfway engagement means and and the lower frame of the suspension device, which lower frame is fixed upon the floor of the automobile. To be little more specific in this respect, laterally of the seat cushion, a base plate is provided, which is formed with a seat belt anchor and a U-shaped stopper member, and further a guide bracket is provided, which has an inverted U-shaped guide flange which is in a halfway engagement with the U-shaped stopper member, thus forming the halfway engagement means. The guide bracket is at its lower side formed with a horizontally elongated slide engagement hole. At the lower frame, a connecting link is rotatably provided, extending upwardly and its upper end portion is slideably engaged in the slide engagement hole of the slideably engagement means, thus forming the slideably engagement link means. The advantage of suspension device, as well as the provision of the the halfway engagement means and the link means between the upper and lower frames, creates an interference against the lowest lowering of the upper frame towards the lower frame, resulting in the difficulty of designing the lowest lowering level of the suspension device which is a hindrance in the design of the same to adapt itself to the one which permits a tall occupant to be seated on the seat cushion within a small-size automobile.